A motor vehicle braking system typically includes a brake rotor (sometimes called a disc brake rotor) located at one or more wheels of the vehicle. The brake rotor generally includes a rotor hat and a rotor cheek. The rotor hat is coupled to a rotatable axle to permit the brake rotor to co-rotate with the wheel when the vehicle is moving. The rotor cheek is an annular segment of the brake rotor that surrounds the rotor hat and includes at least one braking surface against which a brake pad is selectively applied when braking is desired. A pair of mutually opposed braking surfaces are typically present on each side of the rotor cheek to provide better braking capabilities through the selective clamping or gripping of opposed brake pads. Several different rotor cheek configurations have been designed. The rotor cheek may, for example, be solid or it may be vented to help dissipate heat generated at the braking surfaces.
The brake pads are normally carried by a brake caliper in close proximity to the braking surfaces. The brake caliper is supported near the brake rotor by a caliper mounting bracket that is attached to an axle hub, a steering knuckle, or some other local stationary section of the vehicle. A typical structural configuration of the brake caliper allows the brake pads to be selectively applied against the braking surfaces of the rotor cheek by way of a mechanic, hydraulic, pneumatic, or electromagnetic braking response mechanism actuated by depressing a brake pedal located in the driver compartment beneath the steering column. The resultant frictional interaction between the rotating rotor cheek and the non-rotating brake pads decreases the rotational speed of the wheel. The rate at which the rotational speed of the wheel decelerates is dependent on the pressure applied by the brake pads as governed by the braking response mechanism.
Sometimes the application of the brake pads against the braking surfaces causes undesirable vibrations to resonate through the brake rotor, the brake caliper, or both. These vibrations may be felt and heard by the passengers present in the vehicle. High frequency vibrations in the range of about 1,000 Hz to about 18,000 Hz, for example, are often associated with a noise referred to as brake squeal while low frequency vibrations below about 1,000 Hz are often associated with a variety of noises such as brake groan, moan, and howl. Any of these noises may be considered an actual or perceived driving disturbance if produced on a regular basis. The development of a light-weight brake rotor that disrupts vibration propagation during braking and, as a result, substantially subdues noise transmission, would be a welcome contribution to the vehicle braking art along with a method of manufacturing such a sound-damped brake rotor.